Celestia: Mapping the Universe in Four Dimensions

Celestia is an open source application for visualizing the universe
across scales ranging from human-sized to galactic. Users can smoothly
zoom out from the Earth’s surface to distant galaxies and set the
simulation time to observe the universe in the past, present or
future. Since the project began in 2001, contributors have continued
to adapt more and more data to include in Celestia’s model of the
universe. Celestia has gained popularity among educators, who use it
to demonstrate a variety of astronomical phenomena and convey a sense
of humanity’s place in the universe. The program is accurate enough
that it is also used within space agencies for mission visualization.